Teyjus: A λProlog Implementation

The name Teyjus stands ambiguously for a project and a family of systems that are about providing an efficient and robust implementation of the language λProlog. As a project, Teyjus has spanned a period of over fifteen years, involving people from Duke University, SUNY Buffalo, the University of Chicago and the University of Minnesota. As a system, Teyjus has seen two incarnations. Its first version, released in mid-1999, is characterized by a complete support for the operation of higher-order unification. Its second version, released in April 2008, is oriented around a special form of higher-order unification known as pattern unification. The new version also includes modularity notions coupled with a complete form of separate compilation. The work on Teyjus fits into a larger research theme for the group at the University of Minnesota: developing logics and systems for specifying, prototyping and reasoning about computations. In addition to Teyjus, the group has recently played a role in developing systems such as Bedwyr and Abella that can be used to reason about specifications written in a λProlog-like language. Some of this work represents an ongoing collaboration with the Parsifal group at INRIA, Saclay under the aegis of the SLIMMER project. We limit our attention here to the Teyjus system that concerns only the specification and prototyping aspects. A recent article in the newsletter on the Abella system has discussed the reasoning focus and the group members can also be contacted directly for more details about this direction.